Electromagnetic contactors



Jan. 20, 1970 w. A. J. SAUNDERS 3,491,316

ELECTROMAGNETIC CONTAG'IORS Filed Nov. 2, 1967 3 Sheets-Sheet 1 12 H 'Y 49 w 12 1% mum/rm? By r M,

Jan. 20, 1970 w SAUNDERS 3,491,316

ELECTROMAGNETIC CONTACTORS Filed Nov. 2, 1967 3 Sheets-Sheet 2 25 flaws 4g O CO BYM MUM Jan. 20, 1970 w. A. J. SAUNDERS 3,491,316

ELECTROMAGNETIC CONTACTORS Filed Nov. 2, 1967 5 Sheets-Sheet 5 Mun wk Wan/m Amway Jess/w Jam/nae:

United States Patent 3,491,316 ELECTROMAGNETIC CONTACTORS William Arthur Joseph Saunders, Watford, England, as-

signor to Watford Electric & Manufacturing Company Limited, Watford, England, a British company Filed Nov. 2, 1967, Ser. No. 680,219 Int. Cl. H01h 3/60 US. Cl. 335-193 8 Claims ABSTRACT OF THE DISCLOSURE An electromagnetic contactor with a fixed contact and a movable contact resiliently mounted on the armature of an electromagnetic actuator. The fixed contact is mounted in one housing and the stator of the actuator in a second housing removably secured to the first housing. A resilient strip retains the stator in the second housing and absorbs shock produced by the impact of the armature on the stator.

The invention relates to electromagnetic contactors.

According to the invention, an electromagnetic contactor comprises a first housing containing a fixed contact and a movable contact, a second housing which is generally closed and has an opening at one end, the second housing containing an electromagnetic actuator comprising a stator including a core, a coil adapted to be fed with electric current and an armature movable with respect to the core, the armature being arranged when the coil is energised to move the movable contact into contact closure with the fixed contact, wherein the second housing is adapted to be detachably secured at said one end to the first housing and the stator has a portion arranged to limit the movement of the armature in the direction for contact closure, there being provided in the second housing between part of the stator and said one end a resilient member arranged to retain resiliently the actuator in position within the second housing and to absorb shock caused by the impact of the armature on said stator portion.

With the present invention, the aforementioned resilient member serves not only to retain resiliently the actuator in position within the housing but also, by virtue of the resilience of the resilient member serves to absorb shock produced by the impact of the armature on the stator portion (which may be the core). This reduces effects such as contact chatter or bounce. The invention is particularly suitable for an in line contactor, that is, a contactor in which the movement of the armature is aligned with that of the moving contact.

One embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIGURE 1 is a front view of an electrical contactor of the invention,

FIGURE 2 is a side view of the electrical contactor of FIGURE 1,

FIGURE 3 is a section on the line Ill-III in FIG- URE 1,

FIGURE 4 is a segtion on the line IVIV in FIG- URE 2, and

FIGURE 5 is a section on the line VV in FIG- URE 1.

In this example, the electrical contactor is adapted for use in the supply of electric power to a 3 phase, 3 pole electric motor (not shown). The contactor has an insulating rectangular base 16, which is normally mounted in a vertical plane, a rectangular arc box 24 (which, with the base 11, constitutes the aforementioned first housing) open at the front and back and mounted on the base 16, and a hollow cover 41 mounted on the arc box 24. The base 16 is longer than, and projects above and below the arc box 24. Three input terminals 11 are fixed in a row to the projecting part of the base 16 below the arc box 24, and three output terminals 12 are fixed in a rowto the projecting part of the base 16 above the arc box 24.

A pair of fixed contacts 14 and 13, made of a copper/ silver alloy and fixed to the base 16 within the arc box 24, are provided for each pair of input and output terminals 11 and 12 to which they are connected by brass conducting strips 17 and 18 respectively. A moving bridge contact 19 having copper/silver alloy contact pieces 21 and 22 joined by a conducting strip 23 is arranged in front of each pair of fixed contacts 13 and 14. Each bridge contact 19 is mounted on a movable contact carrier 27 and urged away from the carrier 27 by a coil spring 28. A backing leaf spring 29 is positioned between each coil spring 28 and the corresponding strip 23 of the contact 19. Two springs 31 and 32 act on the carrier 27 to urge it away from the fixed contacts 13 and 14. The carrier 27 is movable horizontally towards the fixed contacts 13 and 14 so that the contact pieces 21 and 22 make electrical connection with the fixed contacts 14 and 13 respectively to bridge the gap between them. The carrier 27 may also be moved away from the contacts 13 and 14 so that the bridge contact 19 is moved to break contact with the contacts 13 and 14. The are box 24 surrounds the fixed contacts 13 and 14 and the moving contacts 19 and contains steel arc splitters 26 of various sizes.

The cover 41 (which constitutes the aforementioned second housing) is secured to the base 16 by means of two bolts 40 (see FIGURE 5) which pass through cores in the arc box 24. In this way the arc box 24 is also secured in position.

Within the cover is an electromagnetic actuator comprising a coil 44 mounted on a bobbin 43, an E-shaped laminated core 37 (constituting the operative part of the actuators stator), and an E-shaped laminated armature 38 which is movable relative to the coil 44 and core 37. The electromagnetic actuator is held in position in the cover by a steel spring strip 47. This spring strip 47 is bowed towards the end 50 of the cover 41 and extends across the open end of the cover 41. The ends of the spring strip 47 are removably received in apertures 48 and 49 on opposite sides of the cover 41. The laminated core 37 rests against the spring strip 47 which due to its resiliency urges the core 37 towards the end 50 of the cover 41. A wedge shaped rubber pad 42 is interposed between the upper end 43a of the bobbin 43 and the inside of the end 50 of the cover 41 (see FIGURE 3). A similar pad 42a is interposed between the bobbins lower end 43b and the end 50. The coil 44 has two spring urged terminal connections 5-2 (only one shown) carried by the bobbin 43, Each terminal connection 52 makes contact with the free end of a conducting rod 51 (see FIGURE 5) which is fixed to the base 16 and is connected to a terminal 55 on the base 16 so that electric current can be supplied to the coil 44 via the rod 51 and contact 52 when it is required to energise the coil.

Two pairs of contact sets 53 and 54 are provided, one pair at each side of the contactor and positioned outside the arc box 24. These contact sets 53 and 54 have contact bridge pieces carried on auxiliary contact carriers 56 movable with contact carrier 27 and may be used for any desired subsidiary circuits.

A brass stirrup 33 is positioned between the armature 38 and the contact carrier 27 so that it straddles the spring strip 47 and the core 37. The base of the stirrup 33 rests against the contact carrier 27. The side arms 34 and 36 of the stirrup 33 extend outwardly so that the ends of the arms 36 and 34 abut against two thrust plates 39 and 46 respectively, fixed to opposite sides of the armature 38.

The cover 41 has fins 45 to assist cooling of the contactor.

The contactor shown in the drawings has normally open contacts. When no current is passed through the coil 44, the armature 38 is not attracted to the core 37 and the springs 31 and 32, and also the springs 28, cause the carrier 27 to move away from the fixed contacts 13 and 14 to break electrical connection between the contacts 19 and the contacts 13 and 14. The carrier 27 pushes the stirrup 33 outwards thereby sliding the armature 38 out of contact with the core 37. The gap between the armature 38 and the core 37 is then approximately inch.

When it is desired to close the contactor, a current is passed through the coil 44. The armature 38 is then drawn into contact with the core 37. The motion of the armature is transmitted via the stirrup 33 to the moving contacts 19 to cause them to bridge the gaps between the contacts 13 and 14. In this operation of closing the contactor, the armature 38 moves sufiiciently to cause the moving contacts 19 to make contact with the fixed contacts 13 and 14 before the armature 38 makes contact with the core 37 The shock caused by the subsequent impact of the armature 38 on the core 37 is largely absorbed by the spring strip 47, and this reduces vibration of the moving contacts 19 relative to the fixed contacts 13 and 14 (also known as contact chatter or bounce) and subsequent arcing, when the armature 38 makes contact with the core 37.

To dismantle the contactor, the cover 41 may be removed when the two bolts 40 have been unscrewed, and the arc box 24 may then be lifted off the base 16. The spring strip 47 may be removed from the cover 41 by withdrawing it through one of the apertures 48 or 49, so that the electromagnetic device may be removed from the cover 41. The electromagnetic device may be refixed in the cover 41, by replacing it in the cover 41 and subsequently sliding the spring strip 47 through one of the apertures 48 and 49 until one end of the spring strip has passed across the open end of the cover 41 and reengaged the other of the apertures 48 or 49. The overall height of the contactor is approximately 6% inches. The contactor may be used in the power supply of an electric motor using 60 amps. at 550 volts.

The invention is not restricted to the details of the foregoing example.

I claim:

1. An electromagnetic contactor comprising a first housing containing a fixed contact and a movable contact, a second housing which is generally closed and has an opening at one end, the second housing containing an electromagnetic actuator comprising a stator including a core, a coil adapted to be fed with electric current and an armature movable with respect to the core, the armature being arranged, when the coil is energized, to move the movable contact into contact closure with the fixed contact, said stator and armature being located on the side of the moving contact remote from the fixed contact, wherein the second housing is adapted to be detachably secured at said one end to the first housing and the stator has a portion arranged to limit the movement of the armature in the direction for contact closure, there being provided in the second housing between part of the stator and said one end a resilient retaining member disposed near said one end of the housing and thereby arranged to retain resiliently the actuator in position within the second housing and to absorb shock caused by the impact of the armature on said stator portion.

2. A contactor as claimed in claim 1 wherein the movable contact is resiliently mounted on a carrier moved by the armature.

3. A contactor as claimed in claim 2 wherein there is provided at least one spring buffer between the carrier and the first housing.

4. A contactor as claimed in claim 3 wherein the movement of the armature is aligned with the movement of the movable contact.

5. An electromagnetic contactor comprising a first housing containing a fixed contact and a movable contact, a second housing which is generally closed and has an opening at one end, the second housing containing an electromagnetic actuator comprising a stator including a core, a coil adapted to be fed with electric current and an armature movable with respect to the core, the armature being arranged, when the coil is energized, to move the movable contact into contact closure with the fixed contact, said stator and armature being located on the side of the moving contact remote from the fixed contact, wherein the second housing is adapted to be detachably secured at said one end to the first housing and the stator has a portion arranged to limit the movement of the armature in the direction for contact closure, there being provided a resilient member engaging cooperating parts of said second housing near said one end thereof and abutting a part of said stator, whereby said resilient member resiliently retains said actuator in position within said second housing and absorbs shock caused by the impact of the armature on said stator portion.

6. A contactor as claimed in claim 5 wherein said stator portion is part of said core.

7. A contactor as claimed in claim 6 wherein the resilient member comprises a spring strip.

8. A contactor as claimed in claim 7 wherein the movable contact is resiliently mounted on a carrier linked to the armature for movement colinear thereto; said stator and armature are located on the side of the moving contact remote from the fixed contact; and at least one spring buffer means is located between said carrier and said first housing.

References Cited UNITED STATES PATENTS 3,170,054 2/1965 Lawrence. 3,331,039 7/1967 McGary 335132 3,334,319 8/1967 Herrmann 335-132 3,339,161 8/1967 Conner 335-l93 3,396,354 8/1968 Fisher 335--249 BERNARD A. GILHEANY, Primary Examier H. BROOME, Assistant Examiner 

